1. Field of the Invention
This invention relates to a process for producing homoallyl alcohols of the following formula (I) ##STR3## in which either A.sup.1 or A.sup.3 represents a hydrogen atom, the other represents a single bonding along with A.sup.2 ; R.sup.1, R.sup.2, R.sup.3, R.sup.4, R.sup.5 and R.sup.6 are the same or different and independently represents a hydrogen atom, or an alkyl or alkenyl group with or without being substituted with an hydroxyl group or an alkoxyl group; and Y represents a hydrogen atom, an alkyl group or an alkenyl group.
Homoallyl alcohols of the general formula (I) produced according to the present invention are useful as starting material for producing fragrance chemicals, pharmaceuticals and agricultural chemicals.
2. Description of the Prior Art
Homoallyl alcohols are known as prepared according to the following processes.
A process consisting of dehydration of 3-methyl-1,3-butanediol under heating in the presence of phosphoric acid or iodine gives 3-methyl-3-butene-1-ol with a yield of 35% and isoprene with a yield of 30-35% (Bulletin de la Societe Chimique de France 1964 pp800-804).
A process of catalytic dehydration of 3-methyl-1,3-butanediol in the presence of alumina catalyst, silica-alumina catalyst or calcium phosphate catalyst gives 3-methyl-3-butene-1-ol and 3-methyl-2-butene-1-ol with a maximum combined yield of 50% (Neftekhimiya 3, No. 1, 104-107 (1963)).
These prior art processes have problems from the standpoint of industrial production. That is, raising the conversion ratio of 3-methyl-1,3-butanediol to a satisfactory level for the standpoint of industrial production reduces the yield of 3-methyl-3-butene-1-ol because of the inevitable formation of isoprene.
If phosphoric acid is used for catalyst, inevitable using of equipments made of high corrosion-resistant metals because of corrosive properties of phosphoric acid to metals, makes the facility cost too expensive.
If iodine is used for catalyst, higher cost of iodine is disadvantageous for the process. Also, iodine tends to contaminate the product because of its volatility, which makes its removal essential, and the manufacturing process becomes unpreferably complex.
The method shown in Neftekhimyka 3, No. 1 104-107 (1963) has further a problem that the hourly formed amount of the compound of the general formula (I) per unit volume of catalyst is low while keeping the selectivity ratio at an adequate level.